A database system performs various functions, including defining data tables in an organized fashion according to a user/customer's requirements and specifications. When such a database is defined on a database system, it operates to accept entered data records for storage as data entries in the database. It must also be able to support user queries, which may specify values within certain fields (“columns”) of the stored data, and report back all stored data entries for which the specified columns have the specified values. As needed, the database needs to be able to purge data no longer desired to be kept.
A database system should perform these functions to acceptable levels of performance. That can include, among other things, acceptable query latency times. Different users have different requirements relating to database system performance, and may prioritize their requirements differently. Therefore, a database system may need flexibility as to how it meets the customers' needs.